1. Technical Field
The present disclosure relates to a surgical apparatus having an elongated shaft for laparoscopic and endoscopic procedures. In particular, the disclosure relates to a surgical apparatus having a tensile member extending through the elongated shaft and a preload mechanism for adjusting a tensile force in tensile member.
2. Background of Related Art
Typically in a laparoscopic, an endoscopic, or other minimally invasive surgical procedure, a small incision or puncture is made in a patient's body. A cannula is then inserted into a body cavity through the incision, which provides a passageway for inserting various surgical devices such as scissors, dissectors, retractors, or similar instruments. To facilitate operability through the cannula, instruments adapted for laparoscopic surgery typically include a relatively narrow shaft supporting an end effector at its distal end and a handle at its proximal end. Arranging the shaft of such an instrument through the cannula allows a surgeon to manipulate the handle from outside the body to cause the end effector to carry out a surgical procedure at a remote internal surgical site. This type of laparoscopic procedure has proven beneficial over traditional open surgery due to reduced trauma, improved healing and other attendant advantages.
A steerable laparoscopic or endoscopic instrument may provide a surgeon with a range of operability suitable for a particular surgical procedure. For example, the instrument may be configured such that the end effector may be aligned with a longitudinal axis of the instrument to facilitate insertion through a cannula, and thereafter, the end effector may be caused to articulate or move off-axis as necessary to appropriately position the end effector to engage tissue. When the end effector of a steerable, articulating instrument comprises a pair of jaw members for grasping tissue, the jaw members may need to be oriented relative to the tissue once properly positioned.
Often a steerable endoscopic instrument will include a tensile member extending through the elongated shaft to provide the surgeon with control of the end effector. A tensile member may be coupled to the end effector or a distal portion of the elongated shaft in such a manner that longitudinal motion of the tensile member effects motion in the end effector. For example, a surgeon may manipulate an actuator on the handle to induce longitudinal motion of the tensile to articulate the end effector or to move the pair of jaw members between open and closed configurations. In some instances, providing a surgeon with control over the amount of tension in the tensile member may facilitate operation of the instrument. The instrument may be adjusted to provide a responsiveness or degree of tactile feedback suitable for a particular purpose or preference of the surgeon.